Device, system, and method for processor-based data protection

ABSTRACT

A device, system, and method for providing processor-based data protection on a mobile computing device includes accessing data stored in memory with a central processing unit of the mobile computing device and determining that the accessed data is encrypted data based on a data included in one or more control registers of the central processing unit. If the data is determined to be encrypted data, the central processing unit is to decrypt the encrypted data using a cryptographic key stored in the central processing unit. The encrypted data may also be stored on a drive of the mobile computing device. The encryption state of the data stored on the drive is maintained in a drive encryption table, which is used to update a memory page tables and the one or more control registers.

BACKGROUND

Data security remains a concern across all computer platforms. However,data security is a significant concern on mobile, hand-held computingdevices such as smart phones and tablet computers. The mobility andrelatively small form factor of such devices, while generally desirable,tends to allow for easier misplacement, loss, and theft of mobilecomputing devices. When a mobile computing device is lost or stolen, thedata stored on the device is in jeopardy. Depending on the previous usesof the mobile computing device, the lost/stolen device may includesensitive data such as personal identification data, financial data,medical data, and/or the like.

Typical desktop computers and other immobile and/or non-hand-heldcomputing devices may implement a form of data protection using a typeof software-based data encryption/decryption. For example, some dataprotection solutions for desktop computers employ a whole diskencryption/decryption scheme. However, such software-based dataprotection solutions typically rely on the computational power of thecentral processing unit of the desktop computer, which may besignificantly more powerful than those processors included on mobile,hand-held computing devices. Additionally, some desktop and similarcomputers may include self-encrypting hard disk drives. However, suchhard disk drives typically include a form factor that restricts theiruse in the mobile, hand-held computing devices such as a smart phone ortablet computer.

BRIEF DESCRIPTION OF THE DRAWINGS

The embodiments described herein are illustrated by way of example andnot by way of limitation in the accompanying figures. For simplicity andclarity of illustration, elements illustrated in the figures are notnecessarily drawn to scale. For example, the dimensions of some elementsmay be exaggerated relative to other elements for clarity. Further,where considered appropriate, reference labels have been repeated amongthe figures to indicate corresponding or analogous elements.

FIG. 1 is a simplified block diagram of at least one embodiment of asystem for processor-based data protection on a mobile computing device;

FIG. 2 is a simplified block diagram of at least one embodiment of anenvironment of the mobile computing device of FIG. 1;

FIG. 3 is a simplified block diagram representation of at least onembodiment of control registers of a central processing unit of themobile computing device of FIG. 1;

FIG. 4 is a simplified flow diagram of at least one embodiment of amethod for provisioning the mobile computing device of FIG. 1;

FIGS. 5 and 6 is a simplified flow diagram of a least one embodiment ofa method for securing accessing data using processor-based dataprotection; and

FIG. 7 is a simplified flow diagram of at least one embodiment of amethod for securely storing data using processor-based data protection.

DETAILED DESCRIPTION OF THE DRAWINGS

While the concepts of the present disclosure are susceptible to variousmodifications and alternative forms, specific exemplary embodimentsthereof have been shown by way of example in the drawings and willherein be described in detail. It should be understood, however, thatthere is no intent to limit the concepts of the present disclosure tothe particular forms disclosed, but on the contrary, the intention is tocover all modifications, equivalents, and alternatives consistent withthe present disclosure and the appended claims.

In the following description, numerous specific details such as logicimplementations, opcodes, means to specify operands, resourcepartitioning/sharing/duplication implementations, types andinterrelationships of system components, and logicpartitioning/integration choices are set forth in order to provide amore thorough understanding of the present disclosure. It will beappreciated, however, by one skilled in the art that embodiments of thedisclosure may be practiced without such specific details. In otherinstances, control structures, gate level circuits and full softwareinstruction sequences have not been shown in detail in order not toobscure the invention. Those of ordinary skill in the art, with theincluded descriptions, will be able to implement appropriatefunctionality without undue experimentation.

References in the specification to “one embodiment,” “an embodiment,”“an example embodiment,” etc., indicate that the embodiment describedmay include a particular feature, structure, or characteristic, butevery embodiment may not necessarily include the particular feature,structure, or characteristic. Moreover, such phrases are not necessarilyreferring to the same embodiment. Further, when a particular feature,structure, or characteristic is described in connection with anembodiment, it is submitted that it is within the knowledge of oneskilled in the art to effect such feature, structure, or characteristicin connection with other embodiments whether or not explicitlydescribed.

Embodiments of the invention may be implemented in hardware, firmware,software, or any combination thereof. Embodiments of the inventionimplemented in a computer system may include one or more bus-basedinterconnects between components and/or one or more point-to-pointinterconnects between components. Embodiments of the invention may alsobe implemented as instructions carried by or stored on a transitory ornon-transitory machine-readable (e.g., computer-readable) medium, whichmay be read and executed by one or more processors. A machine-readablemedium may be embodied as any device, mechanism, or physical structurefor storing or transmitting information in a form readable by a machine(e.g., a computing device). For example, a machine-readable medium maybe embodied as read only memory (ROM); random access memory (RAM);magnetic disk storage media; optical storage media; flash memorydevices; mini- or micro-SD cards, memory sticks, electrical signals, andothers.

In the drawings, specific arrangements or orderings of schematicelements, such as those representing devices, modules, instructionblocks and data elements, may be shown for ease of description. However,it should be understood by those skilled in the art that the specificordering or arrangement of the schematic elements in the drawings is notmeant to imply that a particular order or sequence of processing, orseparation of processes, is required. Further, the inclusion of aschematic element in a drawing is not meant to imply that such elementis required in all embodiments or that the features represented by suchelement may not be included in or combined with other elements in someembodiments.

In general, schematic elements used to represent instruction blocks maybe implemented using any suitable form of machine-readable instruction,such as software or firmware applications, programs, functions, modules,routines, processes, procedures, plug-ins, applets, widgets, codefragments and/or others, and that each such instruction may beimplemented using any suitable programming language, library,application programming interface (API), and/or other softwaredevelopment tools. For example, some embodiments may be implementedusing Java, C++, and/or other programming languages. Similarly,schematic elements used to represent data or information may beimplemented using any suitable electronic arrangement or structure, suchas a register, data store, table, record, array, index, hash, map, tree,list, graph, file (of any file type), folder, directory, database,and/or others.

Further, in the drawings, where connecting elements, such as solid ordashed lines or arrows, are used to illustrate a connection,relationship or association between or among two or more other schematicelements, the absence of any such connecting elements is not meant toimply that no connection, relationship or association can exist. Inother words, some connections, relationships or associations betweenelements may not be shown in the drawings so as not to obscure thedisclosure. In addition, for ease of illustration, a single connectingelement may be used to represent multiple connections, relationships orassociations between elements. For example, where a connecting elementrepresents a communication of signals, data or instructions, it shouldbe understood by those skilled in the art that such element mayrepresent one or multiple signal paths (e.g., a bus), as may be needed,to effect the communication.

Referring now to FIG. 1, in one embodiment, a system 100 for providingprocess-based data protection includes a mobile computing device 102 anda security provisioning server 104, which communicate with each other ofa network 106. The mobile computing device 102 may be embodied as anytype of mobile computing device capable of performing the functionsdescribed herein including, but not limited to, a mobile phone, a smartphone, a tablet computing device, a personal digital assistant, amessaging device, a consumer electronic device, a handset, a laptopcomputer, and/or any other mobile computing device configured to storedata locally. In one particular embodiment, the mobile computing device102 has a form factor sized to be held in a hand of the user, such as asmart phone or tablet computer.

As discussed in more detail below, the mobile computing device 102 isconfigured to provide processor-based data protection for data stored onthe device 102 utilizing a central processing unit 110 that includes acryptographic engine 116. The cryptographic engine 116 of the centralprocessing unit 110 facilitates encryption/decryption of locally storeddata using a cryptographic key securely stored in the central processingunit 110. The central processing unit 110 is capable of determining theencrypted/decrypted state of the locally stored data based on dataincluded in one or more control registers of the central processing unit110. It should be appreciated that because the cryptographic key remainssecurely within the central processing unit 110 (i.e., the cryptographickeys of the central processing unit 110 are not exposed to anyapplication executing on, or other device of, the mobile computingdevice 102), the data protection provided by the central processing unit110 is improved relative to typical software-based encryptiontechniques. Additionally, because the cryptographic engine 116 isincorporated within the central processing unit 110, theencryption/decryption of data may be quicker than some software-basedencryption techniques.

As shown in FIG. 1, the illustrative mobile computing device 102includes the central processing unit 110, an I/O subsystem 120, a memory122, a data storage device 124, a communication circuitry 126, and oneor more peripheral devices 128. In some embodiments, several of theforegoing components may be incorporated on a motherboard or main boardof the mobile computing device 102, while other components may becommunicatively coupled to the motherboard via, for example, aperipheral port. Furthermore, it should be appreciated that the mobilecomputing device 102 may include other components, sub-components, anddevices commonly found in a mobile computing device, which are notillustrated in FIG. 1 for clarity of the description.

The central processing unit 110 may be embodied as any type ofprocessor, microprocessor, microcontroller, digital signal processor, orother processing circuitry including the features and capabilitiesdescribed herein. The central processing unit 110 is illustrativelyembodied as a single core processor having a processor core 112.However, in other embodiments, the central processing unit 110 may beembodied as a multi-core processor having multiple processor cores 112.Additionally, in some embodiments, the mobile computing device 102 mayinclude additional processors 110, or other processors, having one ormore processor cores.

As discussed above, the central processing unit 110 includes acryptographic engine 116, which is illustratively embodied in themicrocode 114 of the central processing unit 110. The cryptographicengine 116 is capable of encrypting and decrypting data stored on themobile computing device 102 as discussed in more detail below.Illustratively, the cryptographic engine 116 is configured toencrypt/decrypt data using an Advanced Encryption Standard (AES)symmetric key algorithm in Cipher Block Chaining (CBC) mode. Of course,in other embodiments, the cryptographic engine 116 may utilize othertypes of encryption algorithms and/or other encryption modes.

The cryptographic engine 116 may maintain and/or generate variouscryptographic keys used during the cryptographic functions of the engine116. For example, in the illustrative embodiment, the cryptographicengine 116 includes a cryptographic processor key 130, which isprovisioned in the central processing unit 110 during the manufacturingof the central processing unit 110. In one particular embodiment, thecryptographic processor key 130 is embodied as a one-time-programmable(OTP) fuse that is programmed by a manufacturer of the centralprocessing unit 110. The processor key 130 is maintained within thecentral processing unit 110 in a secure manner such that the processorkey 130 is not exposed or attainable by software or other devices of themobile computing device 102. As discussed in more detail below, thecryptographic processor key 130 is used by central processing unit 110to generate a cryptographic symmetric key 134 (see FIG. 2) that issubsequently used to encrypt and decrypt data stored on the mobilecomputing device 102. Of course, it should be appreciated that althoughonly a single cryptographic processor key 130 is shown in FIG. 1, thecentral processing unit 110 may include additional processor keys inother embodiments.

The I/O subsystem 120 of the mobile computing device 102 may be embodiedas circuitry and/or components to facilitate input/output operationswith the central processing unit 110 and/or other components of themobile computing device 102. In some embodiments, the I/O subsystem 120may be embodied as a memory controller hub (MCH or “northbridge”), aninput/output controller hub (ICH or “southbridge”), and a firmwaredevice. In such embodiments, the I/O subsystem 120 may include a memorymanagement unit 140 configured to manage the memory 122 and interactiontherewith including, for example, establishing and maintaining virtualmemory pages. In other embodiments, however, I/O subsystems having otherconfigurations may be used. For example, in some embodiments, the I/Osubsystem 120 may be embodied as a platform controller hub (PCH). Insuch embodiments, the memory management unit 140 may be incorporated inor otherwise associated with the central processing unit 110, and thecentral processing unit 110 may communicate directly with the memory 122(as shown by the hashed line in FIG. 1). Additionally, in otherembodiments, the I/O subsystem 120 may form a portion of asystem-on-a-chip (SoC) and be incorporated, along with the centralprocessing unit 110 and other components of the mobile computing device102, on a single integrated circuit chip.

In some embodiments, the I/O subsystem 120 may also include a securityengine 150. The security engine 150 may be embodied as a securityco-processor or circuitry configured to perform certain securityfunctions on the mobile computing device 102. For example, as discussedin more detail below, the illustrative security engine 150 is configuredto establish a secured communication link with the security provisioningserver 104 over the network 106 and provide a secure environment forreceiving and responding to communications received from the server 104.

The central processing unit 110 is communicatively coupled to the I/Osubsystem 120 via a number of signal paths. These signal paths (andother signal paths illustrated in FIG. 1) may be embodied as any type ofsignal paths capable of facilitating communication between thecomponents of the mobile computing device 102. For example, the signalpaths may be embodied as any number of point-to-point links, wires,cables, light guides, printed circuit board traces, vias, bus,intervening devices, and/or the like.

The memory 122 of the mobile computing device 102 may be embodied as orotherwise include one or more memory devices or data storage locationsincluding, for example, dynamic random access memory devices (DRAM),synchronous dynamic random access memory devices (SDRAM), double-datarate synchronous dynamic random access memory device (DDR SDRAM), maskread-only memory (ROM) devices, erasable programmable ROM (EPROM),electrically erasable programmable ROM (EEPROM) devices, flash memorydevices, and/or other volatile and/or non-volatile memory devices. Thememory 122 is communicatively coupled to the I/O subsystem 120 via anumber of signal paths (or to the central processing unit 110). Althoughonly a single memory device 122 is illustrated in FIG. 1, the mobilecomputing device 102 may include additional memory devices in otherembodiments. Various data and software may be stored in the memory 122.For example, one or more operating systems, applications, programs,libraries, and drivers that make up the software stack executed by thecentral processing unit 110 may reside in memory 122 during execution.Additionally, as discussed in more detail below with regard to FIG. 2,data used by one or more applications executed on the mobile computingdevice 102 may be stored in an encrypted or unencrypted state in thememory 122.

The data storage 124 may be embodied as any type of device or devicesconfigured for the short-term or long-term storage of data. In theillustrative embodiment, the data storage 124 is embodied as, orotherwise includes, a data drive for long-term storage of data, whichmay be embodied as a hard disk drive, a solid state drive, or otherdrive device. As shown in FIG. 1, the I/O subsystem 120 may include adrive controller 142, which may be embodied as hardware, software, or acombination thereof, to control the drive 124. Additionally, asdiscussed in more detail below with regard to FIG. 2, the mobilecomputing device 102 includes a drive manager module 204 to manage thedata stored on the drive 124. In use, the drive manager module 204monitors the encryption state of data stored on the drive 124 using adrive encryption table 210, which may also be stored on the drive 124 orwithin the memory 122.

The communication circuitry 126 of the mobile computing device 102 mayinclude any number of devices and circuitry for enabling communicationsbetween the mobile computing device 102 and the security provisioningserver 104 over the network 106. The communication circuitry 126 may beconfigured to use any one or more, or combination thereof, communicationprotocols to communicate with the security provisioning server 104 suchas, for example, a wired network communication protocol (e.g., TCP/IP),a wireless network communication protocol (e.g., Wi-Fi®, WiMAX), acellular communication protocol (e.g., Wideband Code Division MultipleAccess (W-CDMA)), and/or other communication protocols.

In some embodiments, the mobile computing device 102 may also includeone or more peripheral devices 128. Such peripheral devices 128 mayinclude any number of additional input/output devices, interfacedevices, and/or other peripheral devices. For example, in someembodiments, the peripheral devices 128 may include a display, keyboard,a speaker system, and/or other input/output devices, interface devices,and/or peripheral devices.

The security provisioning server 104 may be embodied as any type ofdata/web server or similar computing device capable of performing thefunctions described herein. As such, the security provisioning server104 may include devices and structures commonly found in such dataservers such as processors, memory devices, and data storages, which arenot shown in FIG. 1 for clarity of the description. The securityprovisioning server 104 maintains one or more cryptographic keys 160,which may be stored in a database 162 of the server 104. As discussed inmore detail below, the security provisioning server 104 is configured tocommunicate with the mobile computing device 102 over the network 106 toturn on/off the processor-based data protection of the mobile computingdevice 102 and provision the mobile computing device 102 with a sharedsecret key 132 (see FIG. 2). As discussed above, the shared secret key132 may be used by the cryptographic engine 116 of the centralprocessing unit to generate the cryptographic symmetric key used toencrypt and decrypt data stored locally on the mobile computing device102.

The network 106 may be embodied as any number of various wired and/orwireless networks. For example, the network 106 may be embodied as, orotherwise include, a wired or wireless local area network (LAN), a wiredor wireless wide area network (WAN), and/or a publicly-accessible,global network such as the Internet. As such, the network 106 mayinclude any number of additional devices, such as additional computers,routers, and switches, to facilitate communications between the mobilecomputing device 102 and the security provisioning server 104.

Referring now to FIG. 2, in one embodiment, the mobile computing device102 may establish an environment 200 during operation. The illustrativeenvironment 200 includes one or more applications 202, the cryptographicengine 116, the memory management unit 140, and the drive manager module204.

The application(s) 202 may be embodied as any type of software orfirmware application that may periodically request access to data storedon the drive 124. As discussed above, the data stored on the drive 124may be stored in an encrypted or decrypted state. When the application202 requests access to data stored on the drive 124, the drive managermodule 204 retrieves the requested data from the drive 124 and storesthe requested data in the memory 122. As discussed above, the drivemanager module 204 maintains a drive encryption table 210 thatidentifies the state of encryption of data stored on the drive. As such,the drive manager module 204 accesses the drive encryption table 210 todetermine the state of encryption of the retrieved data.

The drive encryption table 210 may be embodied as any type of databaseor data file for storing the encryption information. In the illustrativeembodiment of FIG. 2, the drive encryption table 210 includes anencryption property flag 212 and an encryption state flag 214 for eachdata block (or, in some embodiments, each data file) of the drive 124.The encryption property flag 212 indicates whether data encryption hasbeen enabled for the particular data block of the drive 124, theparticular data file, or the retrieved data (depending on the particularembodiment). If data has been enabled for the retrieved data, the drivemanager module 204 also checks the encryption state flag 214, whichindicates whether the retrieved data is stored in an encrypted state ora decrypted state. The drive manager module 204 provides the encryptioninformation (i.e., the encryption property data and the encryption statedata) to the memory management unit 140.

The memory management unit 140 maintains a memory page properties table220 for organizing and managing the memory 122 (e.g., for establishingvirtual memory on the mobile computing device 102). Similar to the driveencryption table 210, the memory page properties table 220 may beembodied as any type of data file or the like for maintainingmemory-related information. The memory page properties table 220includes header or metadata including encryption information thatidentifies the state of encryption of data stored in the memory 122(i.e., the state of encryption of each memory page of the memory 122).In the illustrative embodiment, the page properties table 220 includesan encryption property flag 222 and an encryption state flag 224 foreach memory page of the memory 122. Similar to the encryption propertyflag 212, the encryption property flag 222 indicates whether dataencryption has been enabled for the particular memory page and, similarto the encryption state flag 214, the encryption state flag 224indicates whether the data stored on the associated memory page isstored in an encrypted state or a decrypted state. After receiving theencryption information from the drive manager module 204, the memorymanagement unit 140 updates the page properties table for the memorypage(s) of the memory 122 wherein the retrieved data is stored with theencryption information. For example, if the retrieved data is encrypted,the memory management unit 140 may set the encryption property flag 222and the encryption state flag 224.

After the page properties table 220 has been updated, the memorymanagement unit 140 notifies the cryptographic engine 116 of theretrieved data stored in the memory 122 (e.g., provides location data ofthe retrieved data), and the cryptographic engine 116 may access theretrieved data. In response to the cryptographic engine 116 accessingthe retrieved data, the memory management unit 140 updates the controlregisters 230 of the central processing unit 110 to reflect theencryption property of the accessed data. Similar to the driveencryption table 210 and the page properties table 220, the controlregisters 230 includes encryption information that identifies the stateof encryption of the retrieved data. In the illustrative embodiment, thecontrol registers include an encryption property flag 232 that indicateswhether data encryption has been enabled for the retrieved data and anencryption state flag 224 that indicates whether the retrieved data isstored in an encrypted or decrypted state in the memory 122. As shown inFIG. 3, the encryption property flag 232 is included in the controlregister 4 (CR4) 300 and the encryption state flag 234 is included inthe control register 3 (CR3) 302. Specifically, the encryption propertyflag 232 is embodied as bit 19 or 20 of CR4 300, and the encryptionstate flag 234 is embodied as bit 6 of CR3 302. Of course, other bits ofthe same or other control registers may be used in other embodiments forthe flags 232, 234.

If the cryptographic engine 116 determines that the retrieved data isencrypted, the cryptographic engine 116 decrypts the retrieved datausing the cryptographic symmetric key 134 and stores the decrypted datain the memory 122. The cryptographic engine 116 may subsequently removeor delete the encrypted data from the memory 122. After the data hasbeen decrypted by the cryptographic engine 116, the central processingunit 110 notifies the application 202 of the location of the decrypteddata in the memory 122.

As discussed above, the cryptographic engine 116 maintains variouscryptographic keys including the cryptographic processor key 130 and thecryptographic symmetric key 134, which is used to encrypt and decryptthe data stored in the memory 122. The cryptographic symmetric key 134is generated by the cryptographic engine 116 using the cryptographicprocessor key 130 and the shared secret key 132 established with thesecurity provisioning server 104. To establish the shared secret key132, the security engine 150 establishes a secured communication linkwith the security providing server 104 using a communication module 208of the mobile computing device 102. The security engine 150 receivessecured communications from the security provisioning server 104, whichare passed to the central processing unit 110 and the cryptographicengine 116. The cryptographic engine 116 establishes the shared secretkey 132 with the security provisioning server 104 using thecryptographic processor key 130 provisioned in the central processingunit 110 at the time of manufacturing. The cryptographic engine 116 andthe security provisioning server 104 may use any suitable algorithm forgenerating the shared secret key 132 such as, for example, aDiffie-Hellman key exchange.

Referring now to FIG. 4, in use, the mobile computing device 102 mayexecute a method 400 for provisioning the shared secret key 132. Themethod 400 begins with block 402 in which the mobile computing device102 determines whether to connect to the security provisioning server104. The mobile computing device 102 may be configured to automaticallyconnect to the security provisioning server 104 (e.g., periodically) orto connect to the server 104 in response to a user's command. If themobile computing device 102 is to connect to the server 104, the method400 advances to block 404 in which the mobile computing device 102establishes a secured communication link with the security server 104.In some embodiments, as discussed above, the security engine 150establishes the secured communication link. In block 406, the sharedsecret key 132 is established between the mobile computing device 102and the server 104. To do so, the mobile computing device 102 may usethe cryptographic processor key 130 in a key exchange (e.g., aDiffie-Hellman key exchange) with the security provisioning server 104to establish the shared secret key 132. The shared secret key 132 isstored in the cryptographic engine 116 of the central processing unit110.

After the shared secret key 132 has been established, the method 400advances to block 408 in which the mobile computing device 102 monitorsfor further secured communications from the security provisioning server104. As discussed below, such further secured communications may includecommands to enable/disable the processor-based data protection on themobile computing device 102. If a secured communication is received fromthe security provisioning server 104, the secured communication isdecrypted in block 410. The secured communication may be decrypted bythe security engine 150 or the cryptographic engine 116 using, forexample, the shared secret key 132. Alternatively, a separate key pairmay be used for the secured communications.

In block 412, the cryptographic engine 116 determines whether thereceived secured communication enables the processor-based dataprotection. If so, the method 400 advances to block 414 in which thecryptographic engine 116 generates the cryptographic symmetric key 134,which is subsequently used for encryption/decryption of data asdiscussed above. In one embodiment, the cryptographic symmetric key 134is embodied as a session key generated as a function of the sharedsecret key 132. However, in other embodiments, the cryptographicsymmetric key 134 may be embodied as a cryptographic key provisioned inthe central processing unit 110 at the time of manufacturing similar tothe cryptographic processor key 130.

In block 416, the processor-based data protection is enabled on themobile computing device 102. In some embodiments, the data size and diskblocks used in the drive encryption table 210 is determined, which arealso used to partition the stored data on the drive 124. Additionally,in some embodiments, any data currently stored on the drive 124 isencrypted in block 420 using the cryptographic symmetric key 134generated in block 414.

Referring back to block 410, if the decrypted secured communication fromthe security provisioning server 104 is determined to disable theprocessor-based data protection in block 422, the method 400 advances toblock 424. In block 424, the processor-based data protection is disabledon the mobile computing device 102. In some embodiments, any currentlyencrypted data stored on the drive 124 is decrypted in block 426 usingthe cryptographic symmetric key 134 stored in the central processingunit 110.

Referring now to FIGS. 5 and 6, when enabled by the securityprovisioning server 104, the mobile computing device 102 may execute amethod 500 for processor-based data protection. The method 500 beginswith block 502 in which the central processing unit 110 determineswhether an application executing on the mobile computing device 102 isrequesting access to a file or data stored on the drive 124. If so, themethod 500 advances to block 504 in which the central processing unit110 requests the file or data from the drive manager module 204. Inresponse, the drive manager module 204 locates the requested data on thedrive 124 and moves the data to the memory 122 in block 506. To do so, adrive storage driver 206 may be used to interact with the drive 124 toretrieve the requested data therefrom. Additionally, in block 508, thedrive manager module 204 updates the memory management unit 140 with theencryption information related to the requested data. To do so, in block510, the drive manager module 204 accesses the drive encryption table210 to determine the encryption status of the data. As discussed above,the drive encryption table 210 illustratively includes an encryptionproperty flag 212 that indicates whether data encryption has beenenabled for the requested data (e.g., for the disk block of the drive124 on which the data is stored) and an encryption state flag 214 thatindicates whether the requested data is encrypted or decrypted.

In response to the encryption information received from the drivemanager module 204, the memory management unit 140 updates, in block512, the page table properties 220 for the memory page for the locationof the requested data in the memory 122. For example, in theillustrative embodiment, the memory management unit 140 may set theencryption property flag 222 and the encryption state flag 224 of thepage table properties 220 in blocks 514, 516 to indicate that dataprotection for the requested data is enabled and that the requested datais in an encrypted state.

In block 518 (see FIG. 6), the central processing unit 110 access therequested data stored in the memory 122. In response, the memorymanagement unit 140 updates the control registers 230 of the centralprocessing unit 110 with the encryption information for the memory pageof the location of the stored requested data in the memory 122. To doso, in the illustrative embodiment, the memory management unit 140 setsthe encryption property flag 232 of the control registers 230 in block520 to indicate that processor-based data protection is enabled for therequested data (or for the associated memory page) and sets theencryption state flag 234 of the control registers 230 in block 522 toindicate the requested data is in an encrypted state. In this way, thecentral processing unit 110 is capable of discovering the encryptionstate of data stored in the memory 122 via use of the control registers230.

In block 520, the central processing unit 110 determines whether theencryption property flag 232 of the control registers 230 has been setto indicate that processor-based data encryption has been enabled forthe requested data. If not, the method 500 advances to block 530 inwhich the central processing unit 110 notifies the application 202 ofthe location of the requested data, which is stored in a decrypted orunencrypted state. However, if processor-based data protection has beenenabled, the method 500 advances to block 522 in which the centralprocessing unit 110 determines whether the encryption state flag 234 ofthe control registers 230 has been set to indicate that requested datais encrypted. If not, the method advances to block 530 as discussedabove. However, if the central processing unit 110 determines that therequested data stored in the memory 122 is encrypted based on thecontrol registers 230, the method 500 advances to block 524 in which thecentral processing unit 110 decrypts the requested encrypted data. To doso, the cryptographic engine 116 of the central processing unit 110decrypts the requested encrypted data using the cryptographic symmetrickey 134, which was used to previously encrypt the data. In block 526,the central processing unit 110 stores the decrypted data in the memory122 in a new location and subsequently removes or deletes the encryptedversion of the requested data from the memory 122 in block 528. In block530, the central processing unit notifies the application 202 of thelocation of the decrypted data in the memory 122. The application 202may subsequently access, process, and/or manipulate the decrypted dataas usual.

Referring now to FIG. 7, the mobile computing device 102 may alsoexecute a method 700 for securely storing data using processor-baseddata protection. The method 700 begins with block 702 wherein theapplication 202 may manipulate or generate data to be stored on themobile computing device 102. In block 704, the central processing unit110 determines whether the application 202 has requested to store dataon the drive 124. If so, the method 700 advances to block 706 in whichthe central processing unit 110 encrypts the data to be stored. To doso, the cryptographic engine 116 of the central processing unit 110encrypts the data using the cryptographic symmetric key 134. Theencrypted data may be temporarily stored in the memory 122 and, in block708, the central processing unit 110 may remove the unencrypted datafrom the memory 122.

In block 710, the encrypted data is provided to the drive manager module204 for storing on the drive 124. The drive manager module 204subsequently stores the encrypted data on the drive 124 in block 712.Additionally, in block 714, the drive manager module 204 updates thedrive encryption table with the encryption information associated withthe encrypted data stored on the drive 124. Such encryption informationmay be provided to the drive manager module 204 by the memory managementunit 140. As discussed above, the drive manager module 204 sets theencryption property flag 212 of the drive encryption table 210 toindicate that processor-based data protection is enabled for the storeddata and sets the encryption state flag 214 of the drive encryptiontable 210 to indicate the stored data is in an encrypted state. In thisway, the encryption information of the stored data may be tracked andsubsequently used when the stored data is later accessed as discussedabove with regard to method 500.

Examples

Illustrative examples of the devices, systems, and methods disclosedherein are provided below. An embodiment of the devices, systems, andmethods may include any one or more, and any combination of, theexamples described below.

In one example, a mobile computing device for processor-based dataprotection may include a memory including data stored therein in anencrypted state and a central processing unit including a cryptographicsymmetric key stored therein and at least one control register. Thecentral processing unit may (i) access the data stored in the memory,(ii) determine that the accessed data is encrypted based on a state of aflag of the at least one control register of the central processingunit, and (iii) decrypt the accessed data using the cryptographicsymmetric key in response to determining that the access data isencrypted.

In an example, the at least one control register may include anencryption property flag that that indicates whether data encryption hasbeen enabled for the accessed data and the central processor is todetermine that the accessed data is encrypted by determining the stateof the encryption property flag. In an example, the central processingunit may include a control register 4 having the encryption propertyflag. In an example, the at least one control register may include anencryption state flag that that indicates whether the access data isstored in an encrypted state or a decrypted state and the centralprocessor is to determine that the accessed data is encrypted bydetermining the state of the encryption state flag. In an example, thecentral processing unit may include a control register 3 having theencryption state flag.

In an example, the central processing unit may include (i) a firstcontrol register having an encryption property flag that that indicateswhether data encryption has been enabled for the accessed data and (ii)a second control register having an encryption state flag that thatindicates whether the access data is stored in an encrypted state or adecrypted state, and the central processing unit is to determine thatthe access data is encrypted by determining the state of the encryptionproperty flag and the encryption state flag. In an example, the mobilecomputing device may further include a drive having data stored thereonand a drive manager module to maintain a drive encryption table thatidentifies the state of encryption of data stored on the drive. In anexample, the mobile computing device may further include a memorymanagement unit to manage the memory. In an example, the drive managermodule may receive a request, from the central processing unit, foraccess to the data stored on the drive, retrieve the requested data fromthe drive and store the retrieved requested data in the memory, accessthe drive encryption table to determine whether the requested data isencrypted, and update the memory management unit with the state ofencryption of the requested data as a function of the drive encryptiontable. In an example, the drive manager module is to access the driveencryption table may determine the state of an encryption property flagstored in the drive encryption table that indicates whether dataencryption has been enabled for the requested data and determine thestate of an encryption state flag stored in the drive encryption ablethat indicates whether the requested data is stored in an encryptedstate or a decrypted state. In an example, the memory management unitmay update a memory page properties table associated with a section ofthe memory in which the requested data is stored with the state ofencryption of the requested data stored in memory. In an example, thememory management unit may update the memory page properties table bysetting an encryption state flag of the memory page properties table toindicate that the requested data stored in memory is encrypted. In anexample, the memory management unit may set an encryption property flagof a first control register of the central processing unit thatindicates data encryption has been enabled for the requested data storedin the memory and set an encryption property flag of a second controlregister of the central processing unit that indicates the requesteddata is stored in the memory of the mobile computing device in anencrypted state.

In an example, the central processing unit may store the decrypted datain the memory and remove the encrypted data from the memory. In anexample, the central processing unit may notify an application executedon the mobile computing device that requested the data of the locationof the decrypted data in memory. In an example, the mobile computingdevice may further include a drive having data stored thereon and thecentral processing unit may receive a request from an applicationexecuted on the mobile computing device to store unencrypted data to thedrive and encrypt, in response to the request from the application, theunencrypted data using the cryptographic symmetric key stored in thecentral processing unit. In an example, the central processing unit mayfurther remove the unencrypted data from the memory of the mobilecomputing device after the unencrypted data has been encrypted by thecentral processing unit. In an example, the mobile computing device mayfurther include a drive manager module to maintain a drive encryptiontable that identifies the state of encryption of data stored on thedrive. The drive manager module may update the drive encryption table toindicate that the encrypted data is stored on the drive in an encryptedstate.

In an example, the central processing unit further include acryptographic processor key that was provisioned in the centralprocessing unit during manufacturing of the central processing unit. Insuch example, the mobile computing device may further include a securityengine to establish a secure communication link with a security serverand establish a shared secret with the security server using thecryptographic processor key. In an example, the cryptographic processorkey is a one-time-programmable fuse located within the centralprocessing unit. In an example, the security engine may receive acommand from the security server over the secure communication link toperform data encryption on the mobile computing device, and the centralprocessing unit may generate, in response to the command received fromthe security server, the cryptographic symmetric key as a function ofthe shared secret. In an example, the mobile computing device mayfurther include a drive having data stored thereon and the centralprocessing unit may encrypt, in response to the command received fromthe security server, data stored on the drive using the cryptographicsymmetric key.

In an example, a method for processor-based data protection on a mobilecomputing device may include accessing, with a central processing unitof the mobile computing device, data stored in a memory of the mobilecomputing device; determining, with the central processing unit, thatthe accessed data is encrypted based on a state of a flag of at leastone control register of the central processing unit; and decrypting, inresponse to determining that the accessed data is encrypted, theaccessed data using a cryptographic symmetric key stored in the centralprocessing unit. In an example, determining that the accessed data isencrypted may include determining the state of an encryption propertyflag of a control register of the central processing unit that indicateswhether data encryption has been enabled for the accessed data. In anexample, determining the state of the encryption property flag mayinclude determining the state of an encryption property flag of controlregister 4 of the central processing unit. In an example, determiningthat the accessed data is encrypted may include determining the state ofan encryption state flag of a control register of the central processingunit that indicates whether the access data is stored in an encryptedstate or a decrypted state. In an example, determining the state of theencryption state flag may include determining the state of an encryptionstate flag of control register 3 of the central processing unit.

In an example, determining that the accessed data is encrypted mayinclude determining the state of an encryption property flag of a firstcontrol register of the central processing unit, wherein the encryptionproperty flag indicates whether data encryption has been enabled for theaccessed data; and determining the state of an encryption state flag ofsecond control register of the central processing unit different fromthe first control register, wherein the encryption state flag indicateswhether the access data is stored in an encrypted state or a decryptedstate. In an example, the method may further include receiving a requestfor access to data stored on a drive of the mobile computing device,moving the requested data from the drive to the memory of the mobilecomputing device, accessing a drive encryption table that identifies thestate of encryption of data stored on the drive to determine whether therequested data is encrypted, and updating a memory management unit ofthe mobile computing device with the state of encryption of therequested data as a function of the drive encryption table. In anexample, accessing the drive encryption table may include determiningthe state of an encryption property flag stored in the drive encryptiontable that indicates whether data encryption has been enabled for therequested data and determining the state of an encryption state flagstored in the drive encryption able that indicates whether the requesteddata is stored in an encrypted state or a decrypted state.

In an example, the method may further include updating a memory pageproperties table associated with a section of the memory of the mobilecomputing device in which the requested data is stored with the state ofencryption of the requested data stored in memory. In an example,updating the memory page table may include setting an encryption stateflag of the memory page properties table to indicate that the requesteddata stored in memory is encrypted. In an example, the method mayfurther include setting an encryption property flag of a controlregister of the central processing unit that indicates data encryptionhas been enabled for the requested data stored in the memory and settingan encryption property flag of a control register of the centralprocessing unit that indicates the requested data is stored in thememory of the mobile computing device in an encrypted state.

In an example, the method may further include storing the decrypted datain the memory of the mobile computing device and removing the encrypteddata from the memory. In an example, the method may further includenotifying an application executed on the mobile computing device thatrequested the data of the location of the decrypted data in memory. Inan example, the method may further include receiving a request from anapplication executed on the mobile computing device to store unencrypteddata to a drive of the mobile computing device, encrypting, in responseto the request from the application, the unencrypted data using thecryptographic symmetric key stored in the central processing unit, andstoring the encrypted data to a drive of the mobile computing device. Inan example, the method may further include removing the unencrypted datafrom the memory of the mobile computing device after the unencrypteddata has been encrypted by the central processing unit. In an example,the method may further include updating a drive encryption table thatidentifies the state of encryption of data stored on the drive withinformation to indicate that the encrypted data is stored on the drivein an encrypted state.

In an example, the method may further include establishing a securecommunication link between the mobile computing device and a securityserver and establishing a shared secret with the security server using acryptographic processor key that was provisioned in the centralprocessing unit during manufacturing of the central processing unit. Inan example, the method may further include receiving a command from thesecurity server over the secure communication link to perform dataencryption on the mobile computing device; and generating, in responseto the command received from the security server, the cryptographicsymmetric key as a function of the shared secret. In an example, themethod may further include encrypting, in response to the commandreceived from the security server, data stored on a drive of the mobilecomputing device using the cryptographic symmetric key.

In another example, a mobile computing device may include a centralprocessing unit and a memory having stored therein a plurality ofinstructions that when executed by the processor cause the mobilecomputing device to perform any of the methods described above. In yetanother example, one or more machine readable media comprising aplurality of instructions stored thereon that in response to beingexecuted result in a mobile computing device performing the any of themethods described above.

In another example, at least one computer-readable storage medium mayinclude a plurality of instructions that in response to being executedresult in a mobile computing device accessing, with a central processingunit of the mobile computing device, data stored in a memory of themobile computing device; determining the state of an encryption propertyflag of a first control register of the central processing unit, whereinthe encryption property flag indicates whether data encryption has beenenabled for the accessed data; determining the state of an encryptionstate flag of a second control register of the central processing unit,wherein the encryption state flag indicates whether the access data isstored in an encrypted state or a decrypted state; determining that theaccessed data is encrypted based on the state of the encryption propertyflags of the control registers of the central processing unit; anddecrypting, in response to determining that the accessed data isencrypted, the accessed data using a cryptographic symmetric key storedin the central processing unit. In an example, the plurality ofinstructions may further result in the mobile computing device receivinga request for access to data stored on a drive of the mobile computingdevice, moving the requested data from the drive to the memory of themobile computing device, accessing a drive encryption table stored onthe mobile computing device that identifies the state of encryption ofdata stored on the drive to determine whether the requested data isencrypted, and updating a memory management unit of the mobile computingdevice with the state of encryption of the requested data as a functionof the drive encryption table.

In an example, accessing the drive encryption table may includedetermining the state of an encryption property flag stored in the driveencryption table that indicates whether data encryption has been enabledfor the requested data and determining the state of an encryption stateflag stored in the drive encryption able that indicates whether therequested data is stored in an encrypted state or a decrypted state. Inan example, the plurality of instructions may further result in themobile computing device updating a memory page properties tableassociated with a section of the memory of the mobile computing devicein which the requested data is stored with the state of encryption ofthe requested data stored in memory. In an example, updating the memorypage table may include setting an encryption state flag of the memorypage properties table to indicate that the requested data stored inmemory is encrypted. In an example, the plurality of instructionsfurther result in the mobile computing device setting an encryptionproperty flag of a control register of the central processing unit thatindicates data encryption has been enabled for the requested data storedin the memory and setting an encryption property flag of a controlregister of the central processing unit that indicates the requesteddata is stored in the memory of the mobile computing device in anencrypted state.

While the disclosure has been illustrated and described in detail in thedrawings and foregoing description, such an illustration and descriptionis to be considered as exemplary and not restrictive in character, itbeing understood that only illustrative embodiments have been shown anddescribed and that all changes and modifications consistent with thedisclosure and recited claims are desired to be protected.

The invention claimed is:
 1. A mobile computing device forprocessor-based data protection, the mobile computing device comprising:a memory device including data stored therein in an encrypted state,wherein the data is associated with an encryption property flag that isset; and a central processing unit including a cryptographic symmetrickey stored therein and at least one control register, wherein the memorydevice is separate from the central processing unit, the centralprocessing unit to: (i) receive a secure command from a security server;(ii) decrypt the secure command; (iii) determine whether the securecommand is a command to enable decryption by the central processingunit, (iv) enable, in response to a determination that the securecommand is a command to enable decryption, decryption by the centralprocessing unit using the cryptographic symmetric key stored therein,(v) access the data stored in the memory device, (vi) determine that thedata accessed in the memory device is encrypted based on a state of acontrol bit of the at least one control register of the centralprocessing unit, (vii) decrypt the data accessed in the memory deviceusing the cryptographic symmetric key in response to determining thatthe data accessed in the memory device is encrypted, and (viii) storethe decrypted data in the memory device with the associated encryptionproperty flag set.
 2. The mobile computing device of claim 1, whereinthe at least one control register includes an encryption state controlbit that indicates whether the access data is stored in an encryptedstate or a decrypted state and the central processor is to determinethat the data accessed in the memory device is encrypted by determiningthe state of the encryption state control bit.
 3. The mobile computingdevice of claim 1, wherein central processing unit includes (i) a firstcontrol register having an encryption property control bit thatindicates whether data encryption has been enabled for the data accessedin the memory device and (ii) a second control register having anencryption state control bit that that indicates whether the dataaccessed in the memory device is stored in an encrypted state or adecrypted state, and wherein the central processing unit is to determinethat the access data is encrypted by determining the state of theencryption property control bit and the encryption state control bit. 4.The mobile computing device of claim 1, further comprising: a drivehaving data stored thereon; and a drive manager module to maintain adrive encryption table that identifies the state of encryption of datastored on the drive.
 5. The mobile computing device of claim 4, furthercomprising a memory management unit to manage the memory device, whereinthe drive manager module is to: receive a request, from the centralprocessing unit, for access to the data stored on the drive, retrievethe requested data from the drive and store the retrieved requested datain the memory device, access the drive encryption table to determinewhether the requested data is encrypted, and update the memorymanagement unit with the state of encryption of the requested data as afunction of the drive encryption table.
 6. The mobile computing deviceof claim 5 wherein the drive manager module is to access the driveencryption table to: determine the state of an encryption propertycontrol bit stored in the drive encryption table that indicates whetherdata encryption has been enabled for the requested data, and determinethe state of an encryption state control bit stored in the driveencryption table that indicates whether the requested data is stored inan encrypted state or a decrypted state.
 7. The mobile computing deviceof claim 5, wherein the memory management unit is to update a memorypage properties table associated with a section of the memory device inwhich the requested data is stored with the state of encryption of therequested data stored in the memory device.
 8. The mobile computingdevice of claim 7, wherein the memory management unit is to: set anencryption property control bit of a first control register of thecentral processing unit that indicates data encryption has been enabledfor the requested data stored in the memory device; and set anencryption property control bit of a second control register of thecentral processing unit that indicates the requested data is stored inthe memory device of the mobile computing device in an encrypted state.9. The mobile computing device of claim 1, the central processing unitfurther to: receive a second secure command from the security server;decrypt the second secure command; determine whether the second securecommand is a command to disable decryption by the central processingunit, and disable, in response to the second secure command, decryptionby the central processing unit.
 10. A method for processor-based dataprotection on a mobile computing device, the method comprising:receiving, with a central processing unit of the mobile computingdevice, a secure command from a security server; decrypting the securecommand; determining whether the secure command is a command to enabledecryption; enabling, in response to a determination that the securecommand is a command to enable decryption, decryption by the centralprocessing unit using a cryptographic symmetric key stored in thecentral processing unit; accessing, with the central processing unit ofthe mobile computing device, data stored in a memory device of themobile computing device, wherein the memory device is separate from thecentral processing unit and wherein the data is associated with anencryption property flag that is set; determining, with the centralprocessing unit, that the data accessed in the memory device isencrypted based on a state of a control bit of at least one controlregister of the central processing unit; decrypting, in response todetermining that the data accessed in the memory device is encrypted,the data accessed in the memory device using the cryptographic symmetrickey stored in the central processing unit; and storing the decrypteddata in the memory device with the associated encryption property flagset.
 11. The method of claim 10, determining that the data accessed inthe memory device is encrypted comprises determining the state of anencryption state control bit of a control register of the centralprocessing unit that indicates whether the data accessed in the memorydevice is stored in an encrypted state or a decrypted state.
 12. Themethod of claim 10, wherein determining that the data accessed in thememory device is encrypted comprises: determining the state of anencryption property control bit of a first control register of thecentral processing unit, wherein the encryption property control bitindicates whether data encryption has been enabled for the data accessedin the memory device; and determining the state of an encryption statecontrol bit of second control register of the central processing unitdifferent from the first control register, wherein the encryption statecontrol bit indicates whether the access data is stored in an encryptedstate or a decrypted state.
 13. The method of claim 10, furthercomprising: receiving a request for access to data stored on a drive ofthe mobile computing device; moving the requested data from the drive tothe memory device of the mobile computing device; accessing a driveencryption table that identifies the state of encryption of data storedon the drive to determine whether the requested data is encrypted; andupdating a memory management unit of the mobile computing device withthe state of encryption of the requested data as a function of the driveencryption table.
 14. The method of claim 13, wherein accessing thedrive encryption table comprises: determining the state of an encryptionproperty control bit stored in the drive encryption table that indicateswhether data encryption has been enabled for the requested data; anddetermining the state of an encryption state control bit stored in thedrive encryption able that indicates whether the requested data isstored in an encrypted state or a decrypted state.
 15. The method ofclaim 13, further comprising updating a memory page properties tableassociated with a section of the memory device of the mobile computingdevice in which the requested data is stored with the state ofencryption of the requested data stored in the memory device.
 16. Themethod of claim 15, further comprising: setting an encryption propertycontrol bit of a control register of the central processing unit thatindicates data encryption has been enabled for the requested data storedin the memory device; and setting an encryption property control bit ofa control register of the central processing unit that indicates therequested data is stored in the memory device of the mobile computingdevice in an encrypted state.
 17. The method of claim 10, furthercomprising: storing the decrypted data in the memory device of themobile computing device; and removing the encrypted data from the memorydevice.
 18. At least one non-transitory computer-readable storage mediumcomprising a plurality of instructions that in response to beingexecuted result in a mobile computing device: receiving, with a centralprocessing unit of the mobile computing device, a secure command from asecurity server; decrypting the secure command; determining whether thesecure command is a command to enable decryption; enabling, in responseto a determination that the secure command is a command to enabledecryption, decryption by the central processing unit using acryptographic symmetric key stored in the central processing unit;accessing, with the central processing unit of the mobile computingdevice, data stored in a memory device of the mobile computing device,wherein the memory device is separate from the central processing unitand wherein the data is associated with an encryption property flag thatis set; determining the state of an encryption property control bit of afirst control register of the central processing unit, wherein theencryption property control bit indicates whether data encryption hasbeen enabled for the data accessed in the memory device; determining thestate of an encryption state control bit of a second control register ofthe central processing unit, wherein the encryption state control bitindicates whether the data accessed in the memory device is stored in anencrypted state or a decrypted state; determining that the data accessedin the memory device is encrypted based on the state of the encryptionproperty control bits of the control registers of the central processingunit; decrypting, in response to determining that the data accessed inthe memory device is encrypted, the data accessed in the memory deviceusing the cryptographic symmetric key stored in the central processingunit, and storing the decrypted data in the memory device.
 19. The atleast one computer-readable storage medium of claim 18, wherein theplurality of instructions further result in the mobile computing device:receiving a request for access to data stored on a drive of the mobilecomputing device; moving the requested data from the drive to the memorydevice of the mobile computing device; accessing a drive encryptiontable stored on the mobile computing device that identifies the state ofencryption of data stored on the drive to determine whether therequested data is encrypted; and updating a memory management unit ofthe mobile computing device with the state of encryption of therequested data as a function of the drive encryption table.
 20. The atleast one computer-readable storage medium of claim 19, whereinaccessing the drive encryption table comprises: determining the state ofan encryption property control bit stored in the drive encryption tablethat indicates whether data encryption has been enabled for therequested data; and determining the state of an encryption state controlbit stored in the drive encryption table that indicates whether therequested data is stored in an encrypted state or a decrypted state. 21.The at least one computer-readable storage medium of claim 19, whereinthe plurality of instructions further result in the mobile computingdevice updating a memory page properties table associated with a sectionof the memory device of the mobile computing device in which therequested data is stored with the state of encryption of the requesteddata stored in the memory device.
 22. The at least one computer-readablestorage medium of claim 21, wherein updating the memory page tablecomprises setting an encryption state control bit of the memory pageproperties table to indicate that the requested data stored in thememory device is encrypted.
 23. The at least one computer-readablestorage medium of claim 21, wherein the plurality of instructionsfurther result in the mobile computing device: setting an encryptionproperty control bit of a control register of the central processingunit that indicates data encryption has been enabled for the requesteddata stored in the memory device; and setting an encryption propertycontrol bit of a control register of the central processing unit thatindicates the requested data is stored in the memory device of themobile computing device in an encrypted state.